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US 20050159746A1
(19) United States
(12) Patent Application Publication (10) Pub. No.: US 2005/0159746 A1
Grob et al.
(43) Pub. Date:
(54)
CERVICAL FACET RESURFACING
IMPLANT
(76)
Inventors: Dieter Grob, Erlenbach (CH); Horace
Jul. 21, 2005
Publication Classi?cation
(51)
Int. Cl.7 ................................................... .. A61B 17/56
(52)
US. Cl. .............................................................. .. 606/61
Winston Hale, Degersheim (CH)
Correspondence Address:
(57)
ABSTRACT
Mark C. Johnson
Rennen Otto, Boisselle & Sklan LLP
The present invention relates to prostheses for treating spinal
Nineteenth Floor
pathologies, and more speci?cally to a system and method
1621 Euclid Avenue
for treating articulating surfaces of cervical vertebrae facet
Cleveland, 01-] 441154191 (Us)
joints. The system includes a superior implant for placement
on a superior articulating surface and an inferior implant for
(21) Appl, No,:
10/762,008
placement on an inferior articulating surface. In addition,
(22) Filed:
Jan. 21, 2004
cervical vertebrae facet joint articular facets.
described is a method for providing articulating surfaces for
Patent Application Publication Jul. 21, 2005 Sheet 1 0f 8
Co1-Co4
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Figure 2B
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Patent Application Publication Jul. 21, 2005 Sheet 6 0f 8
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Patent Application Publication Jul. 21, 2005 Sheet 7 0f 8
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CREATE SPACE BETWEEN SUPERIOR ARTICULAR
FACET AND INFERIOR ARTICULAR FACET
PREPARE THE ARTICULATING SURFACE OF THE INFERIOR
ARTICULAR FACET
l
806
PREPARE THE ARTICULATING SURFACE OF THE SUPERIOR
ARTICULAR FACET
I
K808
PLACE THE INFERIOR IMPLANT ON THE INFERIOR ARTICULAR FACET
I
PLACE THE INFERIOR IMPLANT ON THE SUPERIOR ARTICULAR FACET
Figure 8
Figure 9
Patent Application Publication Jul. 21, 2005 Sheet 8 0f 8
[1000
104
Figure 10
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CERVICAL FACET RESURFACING IMPLANT
[0007] These traditional treatments are subject to a variety
of limitations and varying success rates. Furthermore, none
FIELD OF THE INVENTION
of the described treatments puts the spine in proper align
ment or returns the spine to a desired anatomy. In addition,
[0001] The present invention relates generally to prosthe
ses for treating spinal pathologies, and more speci?cally to
a system and method for treating articulating surfaces of
cervical facet joints.
stabiliZation techniques, by holding the vertebrae in a ?xed
position, permanently limit a person’s mobility. Some pro
cedures involving motion devices have a high incidence of
spontaneous fusion. There is thus a need in the art for a
system and procedure capable of increasing the percentage
BACKGROUND OF THE INVENTION
[0002]
Back and neck pain are common ailments. In many
of good results in disc replacement surgery. In addition,
there is a need in the art for better results than are commonly
achieved through spinal fusions. Further, there is a need in
the art for a system and procedure that permits greater
cases, the pain severely limits a person’s functional ability
and quality of life. Avariety of spinal pathologies can lead
to back pain.
mobility in cases of spinal problems involving only the facet
joints, and for obviating the need for spinal fusion associated
[0003] Through disease or injury, the laminae, spinous
With degenerative and congenital problems of the spine.
process, articular processes, or facets of one or more verte
bral bodies can become damaged, such that the vertebrae no
longer articulate or properly align With each other. This can
result in an undesired anatomy, loss of mobility, and pain or
discomfort. With respect to vertebral articular surface
degeneration, facet joints may shoW a reduced thickness of
cartilage and may advance to entire disappearance thereof.
Furthermore, surrounding the degenerated articular surfaces,
there is bony formation capable of causing neurological
compressions inside either the foramenae or spinal canal.
These facts induce pain Which affect a large part of the
BRIEF SUMMARY OF THE INVENTION
[0008] According to an aspect of the invention, there is
provided a cervical facet resurfacing implant comprising: a
superior implant having an articulating surface and a ?xation
surface and con?gured for secured placement on a resur
faced superior articular facet of a selected cervical vertebra;
and an inferior implant having an articulating surface and a
?xation surface and con?gured for secured placement on a
resurfaced inferior articular facet of a cervical vertebra
population.
immediately above the selected cervical vertebra such that
the articulating surface of the inferior implant interacts With
[0004] The vertebral facet joints, for example, can be
damaged by either traumatic injury or by various disease
processes, such as osteoarthritis, ankylosing spondylolysis,
and degenerative spondylolisthesis. The damage to the facet
the articular surface of the superior implant.
joints often results in pressure on nerves, also called a
“pinched” nerve, or nerve impingement. The result is pain,
misaligned anatomy, and a corresponding loss of mobility.
Pressure on nerves can also occur Without facet joint pathol
ogy, e.g., a herniated disc.
[0005] Degenerative spinal diseases can involve articular
surfaces only, but may also have a more invasive pathology
including traumatic, infectious, tumorous or dysmorphic
(spondylolisthesis, for example) effecting the destruction of
all or part of the articular process. The locking of vertebral
motions by spinal arthrodesis or ligamentoplasty induces,
beyond a spinal stiffness, an increased force on the joint
facets of the adjacent vertebrae above and beloW the fusion,
usually sustained by the considered intervertebral space and
therefore an increase of degeneration of these joint facets.
[0006] One type of conventional treatment of facet joint
pathology is spinal stabiliZation, also knoWn as interverte
[0009] According to another aspect of the invention, there
is provided a facet implant comprising: a generally disk
shaped superior implant having an articulating surface and a
?xation surface and being con?gured for placement on a
resurfaced superior articular facet of a selected cervical
vertebra, the superior implant having a tab extending from
the generally disk-shaped portion of the superior implant,
the tab being con?gured for secured attachment to the lateral
mass of the selected vertebra; and a generally disk-shaped
inferior implant having an articulating surface and a ?xation
surface and being con?gured for placement on a resurfaced
inferior articular facet of a cervical vertebra immediately
above the selected cervical vertebra such that the articulating
surface of the inferior implant interacts With the articular
surface of the superior implant, the inferior implant having
a tab extending from the generally disk-shaped portion of
the inferior implant, the tab being con?gured for secured
attachment to the inferior articular process of the cervical
vertebra immediately above the selected vertebra.
[0010] According to another aspect of the invention, there
bral stabiliZation. By applying intervertebral stabiliZation,
is a method for providing articulating surfaces for cervical
one can prevent relative motion betWeen the vertebrae. By
vertebrae facet joint articular facets comprising of: creating
preventing this movement, pain can be reduced. Stabiliza
tion can be accomplished by various methods. One method
of stabiliZation is spinal fusion. Another method of stabili
a space betWeen a superior articular facet of a selected
cervical vertebra and an inferior articular facet of a cervical
Zation is ?xation of any number of vertebrae to stabiliZe and
prevent movement of the vertebrae. Yet another type of
vertebra immediately above the selected cervical vertebra;
conventional treatment is decompressive laminectomy. This
using a rasp to prepare an articulating surface of the inferior
articular facet for an inferior implant; using a rasp to prepare
an articulating surface of the superior articular facet for a
procedure involves excision of the laminae to relieve com
superior implant; ?xing the inferior implant on the inferior
pression of nerves. With regard to discal prostheses, they
articular facet such that a ?xation surface of the inferior
provide a “space” betWeen tWo vertebral bodies While
implant interacts With the articulating surface of the inferior
articular facet; and ?xing the superior implant on the supe
preserving some motion. They solve the aging intervertebral
disc problem but do not function to reduce the force on
rior articular facet such that a ?xation surface of the superior
posterior joint facets.
implant interacts With the articulating surface of the superior
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articular facet; wherein the articulating surface of the supe
rior implant and the articulating surface of the inferior
implant are con?gured to articulate With one another.
for the attachment of muscles to the vertebrae 12. Connect
ing the transverse process 24 on each side of the body 14 is
a lateral mass 26. TWo inferior articular processes 28 extend
doWnWard from the junction of the laminae 20 and the
BRIEF DESCRIPTION OF THE DRAWINGS
[0011]
FIG. 1 is a lateral elevation vieW of a normal
human spinal column;
[0012]
FIG. 2A is an anterior vieW of a normal human
cervical vertebra;
[0013]
FIG. 2B is a posterosuperior vieW of a normal
human cervical vertebra;
[0014]
FIG. 3 is a posterior perspective vieW of a cervical
vertebral facet joint;
[0015]
FIG. 4 is a lateral elevation vieW of a cervical
vertebral facet joint;
[0016]
FIG. 5 illustrates a cervical facet implant;
[0017] FIGS. 6A-C illustrate a facet implant in conjunc
tion With cervical vertebrae;
[0018]
FIG. 7 illustrates an alternate embodiment of a
cervical facet inferior implant in conjunction With a trans
lateral mass screW;
[0019] FIG. 8 is a How chart generally illustrating a
method for providing articulating surfaces for cervical facet
joint articular facets;
[0020]
FIG. 9 is an illustration of a rasp being used to
prepare an articulating surface;
[0021]
FIG. 10 is an illustration of a rasp; and
[0022]
FIG. 11 is an illustration of an aiming device for
use in positioning a trans lateral mass screW.
DETAILED DESCRIPTION OF THE
INVENTION
[0023] Referring initially to FIG. 1, the human spinal
transverse processes 24. The inferior articular processes 28
each have a natural bony structure knoWn as an inferior
articular facet 32, Which faces doWnWard. On the superior
articular facet 30 is a superior articulating surface 38.
Similarly, a superior articular facet 30 faces upWard from the
junction of the lateral mass 26 and the pedicle 16. On the
inferior articular facet 32 is an inferior articulating surface
40.
[0026] As shoWn in FIGS. 3 and 4, When adjacent ver
tebrae 12 are aligned, the superior articular facet 30 and
inferior articular facet 32 interlock. Capped With a smooth
articular cartilage, the interlocked vertebrae form a facet
joint 36, also knoWn as a Zygapophysial joint. An interver
tebral disc 34 betWeen each pair of vertebrae 12 permits
gliding movement betWeen vertebrae 12. Thus, the structure
and alignment of the vertebrae 12 permit a range of move
ment of the vertebrae 12 relative to each other.
[0027] The facet joint 36 is composed of a superior half
and an inferior half. The superior half is formed by the
vertebral level beloW the intervertebral disc 34, and the
inferior half is formed by the vertebral level above the
intervertebral disc 34. For example, in the C3-C4 facet joint,
the superior portion of the joint is formed by bony structure
on the C4 vertebra (e.g., a superior articular surface and
supporting bone on the C4 vertebra), and the inferior portion
of the joint is formed by bony structure on the C3 vertebra
(e.g., an inferior articular surface and supporting bone on the
C3 vertebra).
[0028]
Turning noW to FIG. 5, an exemplary cervical facet
resurfacing implant according to the present invention is
illustrated. The exemplary facet implant 100 generally has a
superior implant 102 and an inferior implant 104. The
superior implant 102 generally has a disk-shaped portion
column 10 is illustrated. The spinal column 10 is comprised
106 and a tab 108 extending from the disk-shaped portion
106. The disk-shaped portion 106 includes an articulating
of a series of thirty-three stacked vertebrae divided into ?ve
surface 110 and a ?xation surface 112.
regions. The cervical region includes seven vertebrae,
knoWn as C1-C7. The thoracic region includes tWelve ver
tebrae, knoWn as T1-T12. The lumbar region contains ?ve
vertebrae, knoWn as Ll-LS. The sacral region is comprised
of ?ve vertebrae, knoWn as Sl-SS. The coccygeal region
contains four vertebrae 12, knoWn as Co1-Cu4.
[0029] The inferior implant 104 also generally has a
disk-shaped portion 114 and a tab 116 extending from the
disk-shaped portion 114. The disk-shaped portion 114
includes an articulating surface 118 and a ?xation surface
120.
[0030]
It should be noted that the term “disk-shaped” is
[0024] Turning noW to FIGS. 2 and 3, normal human
cervical vertebrae 12 are illustrated. It Will be understood by
those skilled in the art that While the cervical vertebrae 12
not restricted to circular or ovular shapes. A generally
vary someWhat according to location, they share many
square-shaped, hexagonal-shaped, or octagonal-shaped
features common to most vertebrae 12. Each vertebra 12
includes a vertebral body 14. TWo short bones, the pedicles
16, extend backWard from each side of the vertebral body 14
implant. While each of these shapes appear similar from a
lateral perspective and are capable of performing a similar
function according to the present invention, a circular or
to form a vertebral arch 18. At the posterior end of each
ovular disk-shape is preferred.
pedicle 16, the vertebral arch 18 ?ares out into broad plates
of bone knoWn as the laminae 20. The laminae 20 fuse With
each other to form a spinous process 22. The spinuous
process 22 provides muscle and ligament attachment.
[0025]
The transition from the pedicles 16 to the laminae
disk-shaped implant may have multiple sides, such as a
[0031]
Turning noW to FIGS. 6A-C, an exemplary cervical
facet resurfacing implant according to the present invention
is illustrated in conjunction With a facet joint. The superior
implant 102 is con?gured for placement on superior articular
facet 30. The superior implant 102 may be ?xed to the
20 is interrupted by a transverse process 24 that thrust out
superior articulating surface 38 using cemented and/or
laterally on each side from the junction of the pedicle 16 and
cementless ?xation techniques. In an exemplary embodi
ment, the superior implant 106 includes a disk-shaped
the lamina 20. The transverse processes 24 serve as guides
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portion 106, Which has an articulating surface 110 and a
?xation surface 112 and is con?gured for placement on a
rial; a biologic coating; a surface treatment, such as to
facilitate bone ingroWth or cement ?xation; a material
speci?cally prepared superior articulating surface 38.
[0032] The disk-shaped portion 106 of the superior
example, the ?xation surface 112 may have a porous surface
implant 102 may range from about 1 mm thick to about 6
mm thick. In an exemplary embodiment, the thickness of the
superior implant 102 ranges from about 2 mm to about 4
mm. In another exemplary embodiment, the thickness of the
superior implant 102 ranges from about 1.5 mm to about 2.5
mm. The disk-shaped portion 106 of the superior implant
102 may also range from about 3 mm in diameter to about
14 mm in diameter. In an exemplary embodiment, the
diameter of the superior implant 102 ranges from about 6
mm to about 12 mm. In another exemplary embodiment, the
facilitating bone ingroWth; and combinations thereof. For
that is beaded, threaded, textured, etc. Further, the ?xation
surface 112 may have a hydroxyapatite coating or may be
plasma-sprayed. In addition to the examples listed, any
knoWn method of improving ?xation of biologic implants
may be used to improve the interaction of the ?xation
surface 112 and the superior articular facet 30.
[0038] In one exemplary embodiment, the ?xation surface
112 of the superior implant 102 is con?gured to interact only
With the superior articulating surface 38 and does not
interact directly With any other aspect of the superior articu
diameter of the superior implant 102 ranges from about 8
lar facet 30 or the facet joint 36. The ?xation surface 112 of
mm to about 10 mm.
the superior implant 102 may be generally ?at or generally
curved for improved interaction With the superior articulat
ing surface 38.
[0033] The ?xation surface 112 may be generally ?at or
generally curved and is con?gured to interact With the
superior articulating surface 38. The articulating surface 110
[0039]
may be generally curved and may be con?gured to interact
With an articulating surface 118 of the inferior implant 104.
embodiment is generally con?gured to articulate or interact
With the articulating surface 118 of the inferior implant 104.
[0034] Extending from the disk-shaped portion 106 of the
Accordingly, the articulating surface 110 of the superior
superior implant is a tab 108 con?gured to interact With or
for attachment to the lateral mass 26 of the vertebra 12. The
tab 108 may be generally curved so that it matches the
natural curvature of the vertebra 12. For example, the tab
?gured such that it acts as a “female” surface Wherein it is
concave or con?gured to accept a “male” articulating sur
108 and the disk-shaped portion 106 of the superior implant
102 may form an angle ranging from about 110 degrees to
about 160 degrees. In one exemplary embodiment, the tab
108 and the disk-shaped portion 106 of the superior implant
The articulating surface 110 in one exemplary
implant 102 may be generally ?at or generally curved. The
superior implant 102 articulating surface 110 may be con
face 118 of an inferior implant 104. Conversely, the superior
implant 102 articulating surface 110 may also be con?gured
such that it acts as a “male” surface Wherein it is convex or
con?gured to be accepted by “female” articulating surface
102 form an angle ranging from about 120 degrees to about
118 of an inferior implant 104.
150 degrees. In another exemplary embodiment, the tab 108
and the disk-shaped portion 106 of the superior implant 102
[0040] The superior implant 102 may be composed of any
may form an angle ranging from about 130 degrees to about
145 degrees.
[0035] The tab 108 may include a hole or a slot or the like
con?gured to receive a ?xation device, such as a screW or the
like. In other Words, the ?xation device passes through the
hole or slot of the tab 108 and into the lateral mass 26 of the
vertebra 12.
[0036]
The superior implant 102 may have a surface
?xation mechanism for ?xing the superior implant 102, such
as by ?xing the ?xation surface 112, to the superior articu
lating surface 38. The surface ?xation mechanism may be
any ?xation mechanism knoWn in the art, such as at least one
of: one or more pegs, one or more pips, ridges, one or more
grooves, one or more ?ns, and one or more screWs. In an
material commonly used in the art for articulating medical
implants. Such materials include, but are not limited to,
cobalt-chromium alloys, ceramics (alumina ceramic, Zirco
nia ceramic, yttria Zirconia ceramic, etc.), titanium, ultra
high molecular Weight polyethylene (UHMWPE), pyrolytic
carbon, titanium/aluminum/vanadium (Ti/Al/V) alloys, Tan
talum, Carbon composite materials and combinations
thereof. For example, the superior implant 102 may be
generally composed of titanium, but have a UHMWPE
articulating surface. Some materials are more appropriate
for articulating surfaces and some more appropriate for
?xation surfaces, but any materials knoWn in the art for use
With articulating and ?xation surfaces can be used in the
present invention. Such materials are commonly used in
joint arthroplasty and the like.
exemplary embodiment, the surface ?xation mechanism
[0041] The inferior implant 104 is con?gured for place
includes at least one ?n 122. The ?n 122 helps prevent the
ment on inferior articular facet 32. The inferior implant 104
superior implant 102 from migrating along the superior
surface ?xation mechanism may include a plurality of
may be ?xed to the inferior articulating surface 40 using
cemented and/or cementless ?xation techniques. In an
exemplary embodiment, the inferior implant 104 has a
ridges, grouped in regions such that the ridges in different
disk-shaped portion 114, Which has an articulating surface
regions are oriented in different directions. For example, the
surface ?xation mechanism may include four regions on the
?xation surface 112 Where each of the four regions has
ridges oriented in a different direction. The various orien
118 and a ?xation surface 120 and is con?gured for place
ment on a speci?cally prepared inferior articulating surface
40.
articulating surface. In another exemplary embodiment, the
tations of the ridges prevent the inferior implant 104 from
moving in different directions With respect to the superior
articulating surface 38.
[0037] The ?xation surface 112 of the superior implant
102 may also have a porous coating; a porous onlay mate
[0042] The disk-shaped portion 116 of the inferior implant
104 may range from about 1 mm thick to about 6 mm thick.
In an exemplary embodiment, the thickness of the inferior
implant 104 ranges from about 2 mm to about 4 mm. In
another exemplary embodiment, the thickness of the inferior
implant 104 ranges from about 1.5 mm to about 2.5 mm. The
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disk-shaped portion 114 of the inferior implant 104 may also
range from about 3 mm in diameter to about 14 mm in
diameter. In an exemplary embodiment, the diameter of the
inferior implant 104 ranges from about 6 mm to about 12
mm. In another exemplary embodiment, the diameter of the
inferior implant 104 ranges from about 8 mm to about 10
mm.
[0043] The ?xation surface 120 may be generally ?at or
generally curved and is con?gured to interact With the
inferior articulating surface 40. The articulating surface 118
may be generally curved and may be con?gured to interact
With an articulating surface 110 of the superior implant 104.
[0044] Extending from the disk-shaped portion 114 of the
inferior implant is a tab 116 con?gured to interact With or for
attachment to the inferior articular process 28 of the vertebra
12. The tab 116 may be generally curved so that it matches
the natural curvature of the vertebra 12. For example, the tab
116 and the disk-shaped portion 114 of the inferior implant
104 may form an angle ranging from about 10 degrees to
about 70 degrees. In one exemplary embodiment, the tab 116
and the disk-shaped portion 114 of the inferior implant 104
form an angle ranging from about 20 degrees to about 60
degrees. In another exemplary embodiment, the tab 116 and
the disk-shaped portion 114 of the inferior implant 104 may
form an angle ranging from about 30 degrees to about 50
[0048] In one exemplary embodiment, the ?xation surface
120 of the inferior implant 104 is con?gured to interact only
With the inferior articulating surface 40 and does not interact
directly With any other aspect of the inferior articular facet
32, the inferior articular process 28, or even the facet joint
36. The ?xation surface 120 of the inferior implant 104 may
be generally ?at or generally curved for improved interac
tion With the inferior articulating surface 40.
[0049]
The articulating surface 118 in one exemplary
embodiment is generally con?gured to articulate or interact
With the articulating surface 110 of the superior implant 102.
Accordingly, the articulating surface 118 of the inferior
implant 104 may be generally ?at or generally curved. The
inferior implant 104 articulating surface 118 may be con
?gured such that it acts as a “female” surface Wherein it is
concave or con?gured to accept a “male” articulating sur
face 110 of a superior implant 102. Conversely, the inferior
implant 104 articulating surface 118 may also be con?gured
such that it acts as a “male” surface Wherein it is convex or
con?gured to be accepted by “female” articulating surface
110 of an superior implant 102.
[0050] The inferior implant 104 may be composed of any
material commonly used in the art for articulating medical
implants. Such materials include, but are not limited to,
degrees.
cobalt-chromium alloys, ceramics (alumina ceramic, Zirco
nia ceramic, yttria Zirconia ceramic, etc.), titanium, ultra
[0045] The tab 116 may include a hole or a slot or the like
con?gured to receive a ?xation device, such as a screW or the
high molecular Weight polyethylene (UHMWPE), pyrolytic
carbon, titanium/aluminum/vanadium (Ti/Al/V) alloys, and
like. In other Words, the ?xation device passes through the
combinations thereof. For example, the inferior implant 104
hole or slot of the tab 116 and into the inferior articular
process 28 of the vertebra 12.
may be generally composed of a ceramic material or a
cobalt-chromium alloy. Some materials are more appropri
ate for articulating surfaces and some more appropriate for
?xation surfaces, but any materials knoWn in the art for use
With articulating and ?xation surfaces can be used in the
[0046] The inferior implant 104 may have a surface ?xa
tion mechanism for ?xing the inferior implant 104, such as
by ?xing the ?xation surface 120, to the inferior articulating
surface 40. The surface ?xation mechanism may be any
present invention. Such materials are commonly used in
?xation mechanism knoWn in the art, such as at least one of:
joint arthroplasty and the like.
one or more pegs, one or more pips, ridges, one or more
grooves, one or more ?ns, and one or more screWs. In an
[0051]
Turning next to FIG. 7, there is provided an
alternate embodiment of a cervical facet inferior implant in
exemplary embodiment, the surface ?xation mechanism
conjunction With a trans-lateral mass screW. In another
includes at least one ?n, such as the ?n shoWn as 122 on the
exemplary embodiment, the inferior implant 204 is con?g
superior implant 102. The ?n helps prevent the inferior
ured to interact With or attach to a trans-lateral mass ?xation
implant 104 from migrating along the superior articulating
mechanism 202. As shoWn, the trans-lateral mass ?xation
mechanism 202 is a screW, but may be any like ?xation
mechanism.
surface. In another exemplary embodiment, the surface
?xation mechanism may include a plurality of ridges,
grouped in regions such that the ridges in different regions
are oriented in different directions. For example, the surface
?xation mechanism may include four regions on the ?xation
surface 120 Where each of the four regions has ridges
oriented in a different direction. The various orientations of
the ridges prevent the inferior implant 104 from moving in
different directions With respect to the inferior articulating
surface 40.
[0047]
The ?xation surface 120 of the inferior implant 104
may also have a porous coating; a porous onlay material; a
biologic coating; a surface treatment, such as to facilitate
bone ingroWth or cement ?xation; and combinations thereof.
For example, the ?xation surface 120 may have a porous
[0052] For example, the inferior implant 204 may include
a threaded hole 212 either extending from or bored into the
?xation surface 210 of the inferior implant 204. The manner
in Which the inferior implant 204 and the trans-lateral mass
?xation mechanism 202 interact may vary With different
anatomies. For example, it may be preferable to offset the
trans-lateral mass screW 202 from the inferior implant 204
such that When the trans-lateral mass screW 202 and inferior
implant 204 interact, the trans-lateral mass screW 202 is not
perpendicular to the inferior implant 204. The trans-lateral
mass screW 202 may range from about 0 degrees offset from
perpendicular to about 60 degrees offset from perpendicular.
surface that is beaded, threaded, textured, etc. Further, the
[0053] The articulating surface 208 of the inferior implant
?xation surface 120 may have a hydroxyapatite coating or
204 is generally con?gured to articulate or interact With the
may be plasma-sprayed. In addition to the examples listed,
any knoWn method of improving ?xation of biologic
implants may be used to improve the interaction of the
articulating surface 110 of the superior implant 102 shoWn
in FIG. 5. Accordingly, the articulating surface 208 of the
inferior implant 204 may be generally ?at or generally
curved. The inferior implant 204 articulating surface 208
?xation surface 120 and the inferior articular facet 32.
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US 2005/0159746 A1
may be con?gured such that it acts as a “male” surface
Wherein it is convex or con?gured to be accepted by a
The articulating surfaces 38 and 40 may be prepared such
that a bleeding bone bed is created to facilitate bone
“female” articulating surface 110 of a superior implant 102.
Conversely, the inferior implant 204 articulating surface 208
ingroWth for the superior implant 102 and inferior implant
may also be con?gured such that it acts as a “female” surface
[0058] As shoWn in FIG. 9, When the single handed rasp
is used to prepare articulating surface 38 and/or articulating
surface 40, the Working end of the tool may be positioned
Wherein it is con?gured to accept a “male” articulating
surface 110 of a superior implant 102.
104.
rior implant 204 to the inferior articular facet 32. The
inside the space created in process block 802. The rasp may
then be moved from an anterior to a posterior position inside
the facet joint 36 in order to effect a clean and uniform
resection of the created space in the shape and dimension of
trans-lateral mass ?xation mechanism 202 may be any
?xation mechanism knoWn in the art, such as a translaminar
screW. The trans-lateral mass ?xation mechanism 202 may
be made from any material knoWn in the art for medical
?xation devices. For example, the trans-lateral mass ?xation
both implants. In other Words, the articulating surface 38 is
prepared such that its shape and dimension resembles the
superior implant 102 and the articulating surface 40 is
prepared such that its shape and dimension resembles the
inferior implant 104. The anterior/posterior movement of the
mechanism 202 may be made from titanium, titanium/
rasp may be continued until the rasp is too small for the
space created. The rasp may be too small When the space
created is so Wide that the rasp cannot prepare both the
[0054]
A trans-lateral mass ?xation mechanism 202 is
con?gured to interact With the inferior implant 204. The
trans-lateral mass ?xation mechanism 202 secures the infe
aluminum/vanadium (Ti/Al/V) alloys, Tantalum, CrCo,
ceramic, carbon or carbon composite materials.
Turning next to FIG. 8, there is provided a How
articulating surfaces 38 and 40 concurrently. A larger
(thicker) rasp may then be used. Increasingly larger rasps
diagram generally illustrating a method for providing articu
lating surfaces for facet joint articular facets. The overall
ranges from about 4 mm to about 8 mm. In one exemplary
?oW begins at process block 802 Wherein a space is created
embodiment, the rasps are designed to cut only When
betWeen the superior articular facet 30 and the inferior
articular facet 32. It Will be understood by those skilled in
the art that prior to creating the space, it may be preferable
moving in a posterior direction to help prevent injury during
the resurfacing process.
[0055]
or even necessary to expose the facet joint 36 at an effected
level and remove the capsule. The effected level may be
exposed through use of any appropriate procedure, such as
a modi?ed “Wiltse” approach. The creation of the space at
may be used until the created space is increased such that it
[0059] In one embodiment, the steps of process blocks
802, 804 and 806 are repeated on the contralateral side of
facet joint 36 prior to performing the steps of process block
808.
may range, for example, from about 2 mm to about 15 mm.
[0060] Progression then ?oWs to process block 808
Wherein the inferior implant 104 is placed on the prepared/
resurfaced articulating surface 40 of the inferior articular
facet 32. In one exemplary embodiment, the inferior implant
104 is placed such that the disk-shaped portion 114 interacts
With the articulating surface 40 of the inferior articular facet
32, but not With other aspects of the inferior articular facet
In one exemplary embodiment, the space ranges from about
32.
4 mm to about 8 mm. It should be understood that a rasp can
[0061] In one alternative embodiment, a trans-lateral mass
screW 202 is used to secure an inferior implant 204 to the
process block 602 may be accomplished by using a curette
or similar device and by removing the cartilaginous surfaces
of the facet joint 36. In one exemplary embodiment, the
created space is suf?cient for using a rasp on an articulating
surface of an articular facet. The space created betWeen the
superior articular facet 30 and the inferior articular facet 32
be any tool used to scrape, grate, or ?le the facets.
[0056] How progresses to process block 804 Wherein the
articulating surface 40 of the inferior articular facet 32 is
prepared for an inferior implant 104. Such preparation may
be made by a rasp, such as a rasp speci?cally designed for
preparing a surface for the cervical facet implant. Progres
sion then continues to process block 806 Wherein the articu
lating surface 38 of the superior articular facet 30 is prepared
for a superior implant 102. Again, such preparation may be
made by a rasp, such as a rasp speci?cally designed for
preparing a surface for the cervical facet implant.
[0057]
Each of the rasps of process blocks 804 and 806
inferior articular facet 32. In this embodiment, the above
method Would also include using the trans-lateral mass
screW 202 to secure the inferior implant 204 to the inferior
articular facet 32.
[0062]
To facilitate placement of the trans-lateral mass
screW 106, an aiming device such as the device illustrated in
FIG. 11 may be used. The aiming device can be used to
position a drill for creating a trans-lateral mass hole for the
trans-lateral mass screW 202. A drill can then be used to
create the hole, Which may have a diameter of about 2 mm,
depending on the diameter of the trans-lateral mass screW
202.
may be either a single shaft rasp or a double action rasp, such
as those illustrated in FIGS. 10-12 and described in detail
[0063]
herein. The process of preparing the articulating surfaces 38
and 40 of the articular facets 28 and 30 may involve using
multiple rasps of increasing thickness While Widening the
secure the inferior implant 104 to the inferior articular facet
32. In one embodiment, the steps of process blocks 808,
space created in process block 802. For example, a 2 mm
rasp may initially be used, then a 4 mm rasp, then a 6 mm
rasp, then an 8 mm rasp, etc., until a desired result is
contralateral side of facet joint 36 prior to performing the
achieved. In addition, the rasps of process blocks 804 and
806 may be the same rasp. Further, a single rasp can be used
to prepare the articulating surfaces 38 and 40 concurrently.
Once the hole is drilled, the trans-lateral mass
screW 202 can be introduced into the hole and then used to
including any steps associated With the drilling or placement
of the trans-lateral mass screW 202, are repeated on the
steps of process block 810.
[0064] Progression then continues to process block 810
Wherein the superior implant 102 is placed on the prepared/
Jul. 21, 2005
US 2005/0159746 A1
resurfaced articulating surface 38 of the superior articular
facet 30. In one exemplary embodiment, the superior
implant 102 is placed such that the disk-shaped portion 106
interacts With the articulating surface 38 of the superior
articular facet 30, but not With other aspects of the superior
2. The cervical facet resurfacing implant of claim 1
Wherein the superior implant and inferior implant are each
articular facet 30.
generally disk-shaped.
[0065] In one embodiment, the steps of process blocks
802, 804, 806, 808 and 810 are then repeated on the
contralateral side.
[0066]
Turning noW to FIG. 10, a single handed rasp is
illustrated. The rasp 1000 includes a handle 1002 and a shaft
tebra such that the articulating surface of the inferior
implant interacts With the articular surface of the supe
rior implant.
3. The cervical facet resurfacing implant of claim 1
Wherein the superior implant further comprises a tab extend
ing from the generally disk-shaped portion of the superior
implant.
4. The cervical facet resurfacing implant of claim 3
Wherein the tab is con?gured for attachment to the lateral
1004 connecting the handle 1002 to the Working end of the
rasp 1000. Attached to the shaft 804 at the Working end of
mass of the selected cervical vertebra.
the rasp 1000 is a head 1006. The head 1006 has at least one
Wherein the tab is attached to the lateral mass of the selected
cutting surface 1008. In one exemplary embodiment, the
cutting surface 1008 is con?gured to cut When the cutting
cervical vertebra With a screW.
surface 1008 is moved in a ?rst direction (eg when the rasp
is moved from the anterior to the posterior direction of the
facet joint) but not When the cutting surface 1008 is moved
in a direction opposite to the ?rst direction (eg when the
rasp is moved from the posterior to the anterior direction of
the facet joint).
[0067] The rasp 1000 is con?gured to prepare the articu
lating surfaces of a facet joint. In an exemplary embodiment,
the rasp 1000 is con?gured to prepare articulating surfaces
38 and 40 of the articular facets 28 and 30 such that the
shape and dimension of the prepared articulating surfaces
resembles the shape and dimension of the superior implant
1.02 and inferior implant 104. For example, if the superior
implant 102 and/or inferior implant 104 are curved, the head
1006 may be generally curved to properly prepare the
surface for the implant.
[0068] In addition, the rasp 1000 may be made from any
appropriate material commonly used for medical tools. In
one exemplary embodiment, at least part of the rasp 1000 is
made from titanium, although the rasp could also be made
5. The cervical facet resurfacing implant of claim 4
6. The cervical facet resurfacing implant of claim 3
Wherein the tab and the disk-shaped portion of the superior
implant form an angle of from about 110 degrees to about
160 degrees.
7. The cervical facet resurfacing implant of claim 1
Wherein the inferior implant further comprises a tab extend
ing from the generally disk-shaped portion of the inferior
implant.
8. The cervical facet resurfacing implant of claim 7
Wherein the tab is con?gured for attachment to the inferior
articular process of the cervical vertebra immediately above
the selected cervical vertebra.
9. The cervical facet resurfacing implant of claim 7
Wherein the tab is attached to the inferior articular process of
the cervical vertebra immediately above the selected cervi
cal vertebra With a screW.
10. The cervical facet resurfacing implant of claim 7
Wherein the tab and the disk-shaped portion of the inferior
implant form an angle of from about 10 degrees to about 70
degrees.
11. The cervical facet resurfacing implant of claim 1
from any material knoWn in the art.
Wherein at least one of the superior implant and the inferior
implant comprises a surface ?xation mechanism.
[0069] While the present invention has been described in
association With several exemplary embodiments, the
12. The cervical facet resurfacing implant of claim 11
Wherein the surface ?xation mechanism comprises at least
described embodiments are to be considered in all respects
as illustrative and not restrictive. Such other features,
one of: at least one peg, at least one pip, at least one ?n,
ridges, and at least one screW hole.
aspects, variations, modi?cations, and substitution of
equivalents may be made Without departing from the spirit
13. The cervical facet resurfacing implant of claim 12
Wherein the surface ?xation mechanism comprises multiple
and scope of this invention Which is intended to be limited
regions and Wherein each of the regions has at least one
ridge oriented in a different direction than the other regions.
14. The cervical facet resurfacing implant of claim 1
solely by the scope of the folloWing claims. Also, it Will be
appreciated that features and parts illustrated in one embodi
ment may be used, or may be applicable, in the same or in
a similar Way in other embodiments.
What is claimed is:
1. A cervical facet resurfacing implant comprising:
a superior implant having an articulating surface and a
?xation surface and con?gured for secured placement
on a resurfaced superior articular facet of a selected
cervical vertebra; and
an inferior implant having an articulating surface and a
?xation surface and con?gured for secured placement
Wherein the ?xation surface of at least one of the inferior
implant and the superior implant has at least one of: a porous
coating, a porous onlay material, a biologic coating, a
surface treatment, and a material facilitating ingroWth of
bone.
15. The cervical facet resurfacing implant of claim 1
Wherein the articulating surface of at least one of the inferior
implant and the superior implant is composed of at least one
of: cobalt-chromium alloy, ceramic, UHMWPE, pyrolytic
carbon, and Ti/Al/V.
16. The cervical facet resurfacing implant of claim 1
Wherein the inferior implant and superior implant each range
from about 1 mm thick to about 6 mm thick.
on a resurfaced inferior articular facet of a cervical
17. The cervical facet resurfacing implant of claim 1
Wherein the inferior implant and superior implant each range
vertebra immediately above the selected cervical ver
from about 3 mm in diameter to about 14 mm in diameter.
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US 2005/0159746 A1
18. The cervical facet resurfacing implant of claim 1
using a rasp to prepare an articulating surface of the
superior articular facet for a superior implant;
further comprising a trans-lateral mass ?xation mechanism
for securing the inferior implant to the inferior articular
facet.
19. The facet implant of claim 18 Wherein the trans-lateral
mass ?xation mechanism comprises at least one of: a
translaminar screW, a bolt and a ?xation pin.
20. A facet implant comprising:
?xing the inferior implant on the inferior articular facet
such that a ?xation surface of the inferior implant
interacts With the articulating surface of the inferior
articular facet; and
?xing the superior implant on the superior articular facet
such that a ?xation surface of the superior implant
interacts With the articulating surface of the superior
articular facet;
a generally disk-shaped superior implant having an articu
lating surface and a ?xation surface and being con?g
ured for placement on a resurfaced superior articular
facet of a selected cervical vertebra, the superior
implant having a tab extending from the generally
disk-shaped portion of the superior implant, the tab
being con?gured for secured attachment to the lateral
mass of the selected vertebra; and
a generally disk-shaped inferior implant having an articu
lating surface and a ?xation surface and being con?g
ured for placement on a resurfaced inferior articular
facet of a cervical vertebra immediately above the
selected cervical vertebra such that the articulating
surface of the inferior implant interacts With the articu
lar surface of the superior implant, the inferior implant
having a tab extending from the generally disk-shaped
portion of the inferior implant, the tab being con?gured
for secured attachment to the inferior articular process
of the cervical vertebra immediately above the selected
vertebra.
21. The cervical facet resurfacing implant of claim 20
Wherein at least one of the superior implant and the inferior
implant comprises a surface ?xation mechanism.
22. The cervical facet resurfacing implant of claim 21
Wherein the surface ?xation mechanism comprises at least
one of: at least one peg, at least one pip, at least one ?n,
ridges, and at least one screW hole.
23. The cervical facet resurfacing implant of claim 20
Wherein the articulating surface of the superior implant
and the articulating surface of the inferior implant are
con?gured to articulate With one another.
26. The method of claim 24 Wherein each of the steps are
repeated on articular facets on a contralateral side of the
vertebrae facet joint.
27. The method of claim 24 Wherein the created space is
begun With a curette.
28. The method of claim 24 Wherein the created space is
a space sufficient for using a rasp on an articulating surface
of an articular facet.
29. The method of claim 24 Wherein the created space
ranges from about 2 mm to about 5 mm.
30. The method of claim 24 Wherein multiple rasps of
increasing thickness are used to prepare the articulating
surfaces of the superior and inferior articular facets.
31. The method of claim 24 Wherein the articulating
surfaces of the superior and inferior articular facets are
prepared such that the created space is increased to accom
modate the superior and inferior implants.
32. The method of claim 30 Wherein the articulating
surfaces of the superior and inferior articular facets are
prepared such that the shape and dimension of superior
articular facet resembles the superior implant and the shape
and dimension of the inferior articular facet resembles the
Wherein the ?xation surface of at least one of the inferior
inferior implant.
implant and the superior implant has at least one of: a porous
coating, a porous onlay material, a biologic coating, a
surface treatment, and a material facilitating ingroWth of
bone.
33. The method of claim 30 Wherein the created space is
increased such that it ranges from about 4 mm to about 15
mm.
Wherein the articulating surface of at least one of the inferior
34. The method of claim 24 Wherein the articulating
surfaces of the superior and inferior articular facets are
prepared such that a bleeding bone bed is created to facilitate
implant and the superior implant is composed of at least one
bone ingroWth.
of: cobalt-chromium alloy, ceramic, UHMWPE, pyrolytic
carbon, and Ti/Al/V.
superior articulating surfaces are prepared by the same rasp.
24. The cervical facet resurfacing implant of claim 20
25. A method for providing articulating surfaces for
vertebrae facet joint articular facets of comprising:
creating a space betWeen a superior articular facet of a
selected vertebra and an inferior articular facet of a
vertebra immediately above the selected vertebra;
using a rasp to prepare an articulating surface of the
inferior articular facet for an inferior implant;
35. The method of claim 24 Wherein the inferior and
36. The method of claim 24 Wherein at least one rasp is
con?gured to cut When moving in a ?rst direction, but not
When moving in a direction opposite of the ?rst direction.
37. The method of claim 24 further comprising securing
the inferior implant to the inferior articular facet With a
trans-lateral mass ?xation mechanism.